I can't speak from personal experience, meaning I haven't built both and directly compared them, but from what I have read from some of the most knowledgeable Ford builders out there, the ONLY reasons to build a 331 vs. a 347 is if you are restricted by some class rules for the racing you are doing, or if for whatever reason you just want less power. That is it.

I tend to agree. The difference is an addition 16 cu.in.. IIRC, the 347 has a rod ratio close to the the Ford 428 and the Chevy 454, two very well kown and respected engines.

The difference is that those are very large displacement engines with a lot of stroke and not much RPM range. I would think a 347 would need to run much higher RPMs to make good power, which brings into play the stress created by the rod angle.

The difference is that those are very large displacement engines with a lot of stroke and not much RPM range. I would think a 347 would need to run much higher RPMs to make good power, which brings into play the stress created by the rod angle.

Jim, I'm playing devil's advocate here. Personally I favor a short stroke/long rod set up myself. It's my nature to question everything, even things you agree with and look at the flip side as well. IIRC, Coast Automotive produces or produced a 347 that carried a CA smog excemption and was guarenteed for 100K miles. The used even a shorter rod then the regular 347 to keep the wrist pin out of the oil ring land. Theoretically, the shorter rod will make for even a worse rod ratio creating more cylinder wear but Coast gave it the 100K mile blessing.

At some point when I get time to make a long post, I'm going to stir up the hornets nest by questioning the "therories" of big bore/short stroke vs small bore/long stroke and power production. I think I can make some very valid points. I'm sure there are some people out there that have a good idea of what I will say.

Either type of build could make more power than the other based on the totality of the build.
Either type of build could be more reliable than the other based on the totality of the build.

That being said, the only reason I wouldn't go with a 347 would be if I suddenly came into a lot of money and could afford a big-bore 8.2 block with a 3.4" stroke. That would get me somewhere around 360 CID.

The BEST choice would probably be one of the 351W based strokers...say a 408. But, it'd be a bit too tight for me on the '65, I'm afraid. Besides that, I couldn't use my exhaust, intake, etc.

Sounds like a porn star, a "professional" wrestler or a TV bass fishing pro.

I plan on going 347 in the '67. It will never be a daily driver so I'm not worried about getting 100,000 miles out of the motor. Someday the '65 will have either a stroked 351 (408? 427?) or a DOHC 4.6.

I built a 347 in a 1968 302 and aluminum heads and the whole nine yards. It has been really good so far! I only would recommend getting a roller block to use for the cam/lifter combo. That was my only oops. That also eliminates all the need to worry about what oil to use and oil additives and all that garbage. Just make sure to beef up your drive line before. My C4 didnt take to well to that 347- 3 months and it was toast.

Alright I guess I will put in my .02 cents worth here... I purchsed a Eagle forged crank, forged I-beam rods and hyper pistons. I would recomend getting better pistons..forged if you can afford it. Are you going to put nitrous to the car? Forced induction? If so keep in mind about your compression ratio and cylinder head cc's. It all factors I screwed up and forgot about the blower aspect so I have to get new pistons to handle the boost-so I was told. I am running the comp cams XE274H. The cams lift is .520-.523 the duration is 230 and 236 the Lobe angle is 110. Another thing you- what trans are you using rear end-etc? Are these items already beefed up? My stock C4 blew up after about 3 months with that 347. I had it raced built to handle 600 hp so I will be good for now. Just remember any weakness in your drivetrain after the engine rebuild and it will become painfull obvious after you pick up the pieces. Good luck!

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